Process of extracting precious metals from their ores.



'No. 820,810. PATEN'I'ED MAY 15, 1906. S. T. MUFPLY. PROCESS OF EXTRAGTING PREGIQUS METAL$ FROM THEIR ORBS.

APPLICATION TILED AUG. 14, 1905.

UNITED STATES PATENT oFFIon,

SIDNEY T. MUFFLY, ()F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO or "DELA WARE.

COMPANY, OF WILMINGTON,

. PRocss EXTRACT-ENG PRECIOUS METALS FROM THEIR ORES.-

Specification oi Letters Patent. Application filed August 14,1205. Serial No. 274 119.

'ratentecl May 15, 1906.

1'0 II/ZZ whom it may concern.-

Be it known that I, SIDNEY T. MUFFLY, a citizen of the United'Btates, residing in Philadelphia, Pennsylvania, have invented certain Improvements in a Process for Extracting Precious Metals from their Ores, of which the following is a specification. v

One object'of my invention is to provide a process in which not only is the time required for the treatment of a given body of ore greatly reduced over what has hitherto been necessary in cyanid processes, but the amount of cyanid solvent employed is also much less than hitherto. 7

.It is further desired that the process of treating ore shall be so carried out that it shall be possible to save and repeatedly use the cyanid solvent, whose active element,-

cyanogen, to a great extent is evolved in the leaching of ores as hydrocyanic-acid gas and I ordinarily lost at the present time.

I further desire to provide a process in which the labor in connection with the treat ment of ores shall be reduced to a minimum, the whole process being of such efliciency that itshall be commercially possible to treat with pr'ofitlow-grade ores running, for example, about one to two dollars per ton of ore.

Another object of the invention is toprovide a process in which successive bodiesof ore may be continuously treated and in which t e cyanogen" evolved as hydrocyanic acid gas is oyclicly restored to the cyanid solvent and reused.

Thesembjects I attain as hereinafter set forth, reference being had to the accompaing drawing, in which'the figure is a representation, to some extent diagrammatic, of one combination of apparatus for accomplishing my invention.

In carrying out my invention I neutralize the acids or acid salts found in the ore by means of a solution of an alkaline h drate applied to the crushed ore in a neutrallzer. Immediately thereafter I deliver this washed and neutralized ore to the interior of a hermetically-seirled stamp-mortar containing an alkaline cyanid solutlon exposed to the directdownward pressure of compressed air.

This inclosed stamp-mortar forms one end of what ma be described as a closed conduit within wlii consisting,

oh the ore is treated, said conduit beyond said stamp-mortar, of a number of lixiviators connected in series, in which the pulp is successively subjected to fresh' bodies of cyanid solution until it 'is finally delivered as tailings to a device whereby it is removed. The conduit formed by the lixiviators and theirconnections and the stamp-mortar is at all times supplied with air under pressure greater than that of the atmosphere, so that the liquid in this conduit always has direct downward pressure of air upon its surface. 'The hydrocyanic-acid gas evolved in the process of lixiviating is conducted to a suitable condensing or absorbing chamber, where it is dissolved in a cyanid so lution subsequently used in the treatment of further bodies of ore.

In the above drawing I have illustrated one combination of apparatus for carrying out the process, and in this drawing A represents an ore-crusher so constructed and adjusted that the ore delivered from it will be in pieces not exceeding a quarter to half a cubic inch in volume. Connected to this crusher by a chute a is a neutralizer B, connected by means of a pipe 0 with a tank C, there being also connected with said neutralizer, preferably to the lower part thereof, a filter-tank c, in turn connected with a stor ge-tank 0 The neutralizer B'preferably consistsof an inclosed casing having within it a revoluble drum b, upon which are'blades or buckets b, there being any desired driving means for turning the drum, in the present instance a Worm-wheel bflfixed to the drum-shaft, and

' a Worm b meshing with said wheel, to which power supplied;

' The neutralizing solution flows from apparatus B to sump-tanks and after precipltating soluble metallic salts is pumped back to supply-tanks for reusei A stampmortar D, inclosed in an air-tight casing, is connected to the neutralizer B bymeans of a closed conduit b, in which is a conveyer b ,'driven in any desired manner, for the purpose of conveying crushed ore from the neutralizer B to said stamp. This conduit is provided with an automaticvalve b, counterweighted so as to normally remain closed to cut off communication between the interior of the stamp-mortar and the neutralizer B, the valve, however, being capableof placed upon it.

An air-compressor E, provided with a neservoir e and a heatlng-chamber e 1s connected so as to supply air to the interior of the stamp-mortar either through a pipe 6 which is placed to deliver air adjacent to the dies and stamps for the purpose hereinafter mentar casing, or through both of said pipes.

\ to su ply heat to the compressed air.

.anumber of tanks h Pu p and liquid from the stamp-mortar is conducted through a conduit f to the first of a series of lixiviators F, connected in series and so arranged that the last of them delivers the sand or tailings to an inclosed bucket conveyer G, delivering into tanks, such as are shown at g.. Liquid from the lixiviators F may be drawn from the bottom of the inclosed 'conveyer-casin G through a pipe g into any of a series 0 filter-tanks 9 Connection, is made between the air-compressor and each of the lixiviators F through branch pipes connected to a pi e e, in addition to which each of said lixlviators, as well as the stamp-mortar, has connected to it branches from a pipe h in connection with any or all of The last of thelixiviators F is connected by a pipe k to a condensing or vapor-absorbing chamber H, in which are placed a number of preferably porous partitions on baflles designedto be kept moistened bya solution delivered from asuitable tank h Liquid from this condensingchamber may pass through suitable pipes to the tanks h while-the tank h is arranged to deliver into it.

" The box I is connected by a pi e i with the chamber H and has some form 0 valve 'i, de-

signed to be automatically and periodically opened by a rod '8 actuated by ratchet mechan sm driven from the driving means of the lixiviators F. In the present instance these lixlviators are of the same construction as the neutralizer B, and they are all driven by a i common shaft through belts which drive the tank C, which solution preferably consists of an alkaline hydrate, such as sodium or potassium hydrate. This solution is, de-

signed to neutralize any acid saltswhich may be resent in the ore due to the oxidation of sul dsor as a' result of'the action of water on decaying vegetable matter. The revolution of the drum 6 of the neutralizer B deposits the neutralized andwashed ore upon the iconveyer' b which delivers it to the counterthe stamp.

saasio weighted valve b and this automatically. operates to discharge said ore into the stampmortar D. The interior of the stamp-mortar is filled with a weak cyanid solution, which may vary from .1 or less to .5 ofone per cent, as the nature of an ore'may require, this being delivered from the tanks it. delivered from the compressor 'E through pipe 6 to the interior of the stamp mortar,

and suchair is refera'bly kept at a tempera-' ture of 60 or 'gher and is at a pressure of ten pounds or greater to the square inch..

If the ore under treatment is of a'slaty or argillaccous nature, it may be also advisable to deliver air under pressure through the pipe 6 in order to prevent the pulp or ore clo ging Screens of any desiredmes are provided at .11 so that the pulp delivered from the stamp is under a certaln fineness,

and this pulp, with a portion of the weak cyanid solution, flows to the various lixiviators F, where the pulp is brought into intimate Air is also contact with-a succession of fresh bodies of cyanid solution, which are atall times-exposed to an air-pressure greater than that of the atmosphere acting directly downwardly upon their surfaces and which'is delivered through pipes e.

I have found that the direct downward pressure of air greater than that of the atmosphere and exerted upon the surface of the cyanid solution very materially hastens the solventaction of the cyanid solution, and as a consequence by this means I am enabled to accomplish one of the important objects of my inventionnamely, the shortening of the time necessary to treat a given body of ore.

'I have also found that by treating the ore within a closed container and under air-pressure acting directly downward upon the sur-- face of the solution said solution is caused to extract a much larger percentage of metal ICO from the ore, in some cases practically all of I it, where-hitherto it has been possible to extract by the cyanid process but a comparatively small amount ,of it, .de ending upon the com lex or free nature oft e ore.

IIO

It wil be understood that the chemical re- I actions occurring in the treatment of a body of ore with a solution of a cyanid necessarily result in the freeing of relatively large amounts of hydrocyanic gasas, for example, by reason of the ferrous sulfate and free sulfuric acid produced .by the atmospheric oxidatioii of iron pyrites reacting upon the solution of potassium cyanid, thus:

2KCN+H2SOr 2HCN+K2SO4,

or by the action of carbon dioxid absorbed from the atmosphere, thus:

2KoN.+oo2+H2o:K2oo8+2non In addition to the above reactions, which obviously result in the liberation of hydrocyanicas cyani solution abso cyanogen, due to eva oration, as well as from other causes which ave not been satisfactorily determined. Instead of allowin this gas to escape and go to waste, as has hit erto een the custom, I cause it, with air under pressure,jto pass out of the lastof the lixiviators F throu h the pi e k and deliver it to a condensing-c amber In this latterI rovide a series of partitions and bafies of urlap or other fabric saturated with a solution, preferabl containing a double cyanid, such of otassium and bromin. This rbs the hydroc anic-acid gas by reason of the fact that sai soluble in Water, but also-for the reason that the resence of the bromin compound material y assists and accelerates such solution,

gas .is not only and I cause it to be delivered from time to time or continuously to the tanks h, from whence 1t is permitted to flow to the stampmortar and t e various lixiviators, where it is used again to treat ores.

- box I, t

tently opened by action of the ratchet meohtion of the The particular process of absorbing the hydrocyanic-acid gas referred to above forms the subject of a separate ap lication for United States Patent, Serial 0. 281 ,674', filed by me October 6, 1905.

In order to stop the passage of any compounds or vapors of base metallic salts which are frequently'found to be carried with the hydrocyanic-acid gas and the compressed air, I deliver into the condensing-chamber a soluthereby forming hydrates with base metallic compounds so entering, which remain in the chamber H.

.The compressed air is periodically allowed to esca e from the chamber H through the e valve i" on this box being intermitanism upon the rod '5 From the last lixiviator F the ore pulp or tailin s, from which the gold and silver has been issolved, pass into inclosed conveyer G and are carried y buckets to covered tank 9,

.containing wash-water, to recover a small amount of the metals remaining in the cyanid moisture. After removing the wash-water for further use the tailings are then discharged from the tanks g to a waste-dump or if containing valuable by-products to some other desired place by means of a sand-pump.

The cyanid solution containing the precious metals is drained from the conveyer 'G through the ipe g into tanks y, where it is filtered and om which it flows to storagetanks for treatment in a series of electrolytic or other apparatus (not shown) forpreci itagold and silver, the solutlon t ere raised by a pump (not shown) to strengthened with fresh cyanidafter bein tanks an solvent compound for further use in treating p Itwill be understood" by those skilled in the art that b regenerating and reusin the cyanogen evo ved as hydrocyanic-aci gas during the carrying out of my improved procass I am enabled to greatly reduce the cost of operation of'the same, slnce the cyanid greatly lessened, but a very much greater proportion of the precious metals contained therein is caused to be dissolved by the cyanid than has hitherto been considered possible. i

I claim as my invention- 1. The process of treating ores which con sists in pulverizing said ores while'they are immersed in a solution capable of dissolving the contained gold and silver, said solution being exposed .to air under pressure eater than that of the atmosphere, described. a

2. The process of treating ores which consists in subjecting them to the action of a cyanid solution exposed to constantly-renewed bodies of air under pressure greater than that of the atmosphere, collecting the hydrocy- 1 anic-acid gas evolved, passing the as with air to a solvent liquid, dissolving sai gas in the liquid and afterward permltting said an to escape, substantially as described. tion of ammonic hydrate from the vessel 7L .3. The process of treating ores which consists in continuously conveying them through successive bodies of a cyanid solution exposed to the action of compressed air, passmg the-hydrocyanic-acid gas evolved and the air through liquid capable of dissolving sald as, and using said 'hquid to act on further %odies of ore, substantially as described.

4. The process of treating ores which cone sists in actingupon them bya solution of cyanid, dissolving the hydrocyanic acid gas evolved in a solution ofa double cyanid, and using said solution to act on further bodies of ore, substantially as described.

5. The process of treating ores which con sists in acting upon'them bya solution of cyanid, dissolving the hydroc'zyanic-amd gas evolved in a solution of a double cyanid and a hydrate compound, and using said solution to act on further bodies of ore, substant1ally as described.

6. The process of treating ores which c0nsists in continuously conveying the ulver ized ores through successive bodies 0 a cyasubstant1ally as i nid solution under a. direct downward airpressure greater than that of the atmosphere, substantially as described.

. 7. The process of treating ores which consists incontinuously conveying the pulverized ores through a cyanid solution exposed to direct downward pressure of constantlyrenewed bodies of compressed air, absorbing &

the hydrooyanic-acid gas evolved in a body tion, substantially as described.

9. The process of treating ores which consists in pulverizing said ore within a cyanid solution, then conveying said ore through successive bodies of a solution under air having-a direct downward pressure greater than that of the atmosphere, substantially as described.

10. The rocess of treating ore which consists in pu verizing said ore within a cyanid solution after neutralizing acid salts in the same, then conveying said ore through successive bodies of cyanid solution under-a direct downward air-pressure greater than that of theatmosphere, said air being maintained at a temperature above the normal, substantially as described.

11. The process of treating ores and extracting gold and silver therefrom, which consists in rapidlyand continuously passing them through an alkaline hydrate solution and immediately thereafter conveying them through an alkaline cyanid solution under a direct downward air-pressure greater than that of the atmosphere, substantially as described.

12'. The process of treating ores which consists in subjecting them to an alkaline hydrate solution and immediately thereafter subjecting them to the combined action of an alkaline cyanid solution and air of an equable temperature having a direct downward pressure upon the solution greater than that of the atmosphere, substantially as described.

13. The process of treating ores continuously for the extraction of gold and silver, which consists in acting upon them with an alkaline neutralizing solution, then immediately thereafter conveying and subjecting them to a cyanid-solvent solution in the presence of heated air having a direct downward pressure upon the solution greater than that of the atmosphere; and passing the hydrocyanic-acid fumes to and absorbm same in a compound alkaline cyanid and alialine hy-. drate solution; and at same time precipitating base-metal vapors arising with the hydrocyanic-acid fumes, substantially as described.

i 14. The process of treating ores to extract the gold and silver they contain, which consists in crushing the ore and neutralizing the acid salts in same, immediately conveying and pulverizing the said ores in an alkaline .cya nid solution under air-pressure greater than that of the atmosphere; immediately and continuously conveying the ores through Y other bodies of cyanid solutions also under air-pressure greater than that of the atmos-v phere and forcing the hydrocyanic-acid fumes through and absorbing same in a com ound alkaline cyanid and alkaline hydrate so ution, using said solution in the treatment of further bodies of ore and simultaneously precipitating vapors of base elements arising -w1th the hydrocyanic-acid fumes, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' SIDNEY T. MUFFLY.

Witnesses:

7WILLIAM E. BRADLEY,

Jos. H. KLEIN. 

